As is known, during this braking action, a noise is often generated which reveals itself as a particularly irritating hiss, which reduces the travel comfort.
The generation of this kind of noise is ascribed to the onset of vibratory effects which involve the various brake components, among which there are also the pads.
Intensive research has been conducted aiming at providing techniques which allow reducing or eliminating noisiness during braking.
One of these techniques suggests to connect a load, by means of a resilient body, to a disc brake component that may be involved in the vibration. According to this technique, any vibration of this brake component is transmitted to the load, which, at low frequencies, oscillates in phase with the component to which it is connected. As the vibration frequency increases, the shift of the oscillations of the load and brake component will increase to a phase opposition condition, at which the component vibration is either reduced or eliminated. Furthermore, according to this technique, the load can be alternatively applied to the piston, caliper body or pad.
This technique requires for the entire brake structure to be specifically designed.
This design is required in order to provide a suitable resilient intermediate element to be arranged between the brake component of which the oscillations are to be reduced, and a suitable load, and also to provide a seat within which the load can oscillate thereby deforming the resilient body.
The requirement of changing the brake structure thus dramatically in order to reduce the hiss effect is a serious drawback. In fact, due to the complexity of the effects occurring during a braking action, and since they depend on a particular application, i.e. the type of vehicle on which the disc brakes are used, a solution that proves to be optimum based on theoretical simulations can however result unsatisfactory following testing or when used in applications other than those provided for.
Accordingly, those solutions that do not have a strong impact on the whole structure of the brake disc are particularly interesting. One of the possible solutions that have been tested is described in U.S. Pat. No. 6,994,190, which provides for loads or masses to be screwed to the pad plate or fixed thereto by means of rivets or welding.
This solution has proved to be very effective in eliminating the vibrations causing irritating hiss but suffers from several drawbacks during the manufacturing step, in that all the embodiments provided in said document are quite complex and require that much care is taken during the step of fixing the loads to the plates.